Arise, Sir Optimus Prime, for King Arthur is actually coming to the world of the Transformers.

It sounded crazy enough when it was just a rumour, but now it looks like Liam Garrigan is set to take up the role of the legendary figure in the upcoming fifth Transformers film, Transformers: The Last Knight.

While there's no official plot synopsis yet, it current seems that Optimus Prime (voiced by Peter Cullen) meets the wizard Merlin in the search for a mysterious artefact that can help restore his destroyed world.

Garrigan's casting is certainly a step toward confirming this rumour, and at least we know the role will be in good hands, as he's already had experience of playing King Arthur on ABC's Once Upon a Time.